Download the App!

Get 24/7 study help with the Numerade app for iOS and Android! Enter your email for an invite.

Get the answer to your homework problem.

Try Numerade free for 7 days

Like

Report

Review Conceptual Example 7 as background for this problem. A car is traveling to the left, which is the negative direction. The direction of travel remains the same throughout this problem. The car's initial speed is $27.0 \mathrm{m} / \mathrm{s},$ and during a 5.0 $\mathrm{s}$ - interval, it changes to a final speed of (a) 29.0 $\mathrm{m} / \mathrm{s}$ and $(\mathrm{b}) 23.0 \mathrm{m} / \mathrm{s}$ . In each case, find the acceleration ( magnitude and algebraic sign) and state whether or not the car is decelerating.

(a) $a=-0.4 \mathrm{m} \cdot \mathrm{s}^{-2}$(b) $a=+0.8 \mathrm{m} \cdot \mathrm{s}^{-2}$

Physics 101 Mechanics

Chapter 2

Kinematics in One Dimension

Motion Along a Straight Line

Rutgers, The State University of New Jersey

University of Michigan - Ann Arbor

Simon Fraser University

McMaster University

Lectures

04:34

In physics, kinematics is …

07:57

In mathematics, a position…

02:16

Refer to Multiple-Concept …

03:47

Multiple-Concept Example 9…

03:04

In preparation for this pr…

06:47

Car $A$ is parked along th…

08:26

A train has a length of 92…

04:40

Constant AccelerationC…

01:33

Constant AccelerationF…

02:20

Physics The acceleration o…

06:42

This question concerns the…

01:14

See Sample Problem $\bolds…

08:57

According to recent test d…

03:43

Constant AccelerationI…

02:47

Review Conceptual Example …

06:39

Consult Multiple-Concept E…

05:01

See Multiple-Concept Examp…

04:49

see Sample Problem $D$ A c…

04:26

An object moves so that it…

01:37

07:59

A remote-controlled car is…

03:34

Additional ProblemsA c…

So in this problem, we're looking at two scenarios for a car. Um and we're analyzing its motion trying to find the acceleration of the car in two different scenarios. Now, for any of these problems, you always want to start from the same way, which is what you see on the screen in front of you right now. Where for the first part part, eh? I have my five variables for the Kenna Matic equations written down V B, not a tea and acts. Now, when we read through this problem, there's a few things we know for this first set up. First of all, the car is starting out, going 27 meters per second to the west. So this V value will initially be 27 meters per second. Now, over the course of five seconds, so I can fill in my tea value. The car's going to accelerate to 29 meters per second, so it is speeding up as it travels in the westward direction. So for this problem, we now know three unknowns, which is what we want. Because in order to use any of the Kinnah Matic equations you see on the right side of the screen. You need to know three of them in order to find 1/4. And the way we pick which of these equations we want to use is by looking at what piece of information we want to know and what piece of information we currently do not have and also don't need to find. So right now, the problems asking for us to find acceleration, which means the variable we don't know and don't need to know is displacement this X value. So the one I just crossed out the ex that tells us which equation to use because when we look over at the Cannes A Matic equations were going to use whichever one does not use the Letter X. And so these three all have acts featured prominently in them, Which means our equation for this first problem is going to be that top equation. The V equals V not plus 80. Um, before we solve this since this one and part B are both looking for acceleration and actually going to rearrange this equation to find what acceleration is equal to. So we have the minus V not equals 80 NFL divide both sides by t you end up with the acceleration equation of V equals or a equals V minus B not divided by Todd. So let's go ahead and plug our numbers in here. Um, for part ay, that gives us 29 minus 27 divided by the time of five. And when we plugged that in, we get an acceleration of 0.4 meters per second squared. Okay. And that is part A. So there's a small positive acceleration for part A. Um, let's look at what we're doing for part B here in the second group I have. So the starting conditions are actually the same. We have 27 meters per second is the starting speed and it also happens over a five second interval. But this time we're slowing down to 23 meters per second. Now the first thing that should be apparent is in the first case, we were accelerating. We were speeding up from 27 to 29 in part be here. We're actually slowing down. We're decelerating from 27 meters per second to 23 meters per second. Um, so we should expect our acceleration to come out as a negative value. In addition to that, um, we should also expect it to be a larger number, a bigger magnitude acceleration, because I'm actually losing four meters per second where before I was gaining too. So the magnitude of this change is bigger. So when I plug in my numbers, I have 23 my final minus 27 my initial divided by five. And this gives us a negative 0.8 meters per second squared, meaning it is slowing down, um, and reducing its speed by that much. And our predictions held out, it is both a negative value, meaning it is slowing down, and it is a larger magnitude than part.

View More Answers From This Book

Find Another Textbook

In physics, kinematics is the description of the motion of objects and syste…

In mathematics, a position is a point in space. The concept is abstracted fr…

Refer to Multiple-Concept Example 5 to review a method by which this problem…

Multiple-Concept Example 9 illustrates the concepts that are pertinent to th…

In preparation for this problem, review Conceptual Example 7 From the top of…

Car $A$ is parked along the northbound lane of a highway, and car $B$ is tra…

A train has a length of 92 $\mathrm{m}$ and starts from rest with a constant…

Constant AccelerationCars $A$ and $B$ move in the same direction in adja…

Constant AccelerationFigure $2-27$ shows a red car and a green car that …

Physics The acceleration of an object is a measure of how much its velocity …

This question concerns the motion of a car on a straight track; the car'…

See Sample Problem $\boldsymbol{B}$ A car traveling in a straight line has a…

According to recent test data, an automobile travels 0.250 $\mathrm{mi}$ in …

Constant AccelerationIn Fig. $2-27,$ a red car and a green car, identica…

Review Conceptual Example 5 before beginning this problem. You are traveling…

Consult Multiple-Concept Example 11 in order to review a model for solving t…

See Multiple-Concept Example 9 for the basic idea behind problems such as th…

see Sample Problem $D$ A car starts from rest and travels for 5.0 s with a u…

An object moves so that its position changes in the following way: $x(t)=-10…

Review Conceptual Example 16 as background for this problem. The water skier…

A remote-controlled car is moving in a vacant parking lot. The velocity of t…

Additional ProblemsA car moving with constant acceleration covered the d…

04:30

A bicyclist makes a trip that consists of three parts, each in the same dire…

02:21

(a) Suppose that a NASCAR race car is moving to the right with a constant ve…

02:30

A motorcycle has a constant acceleration of 2.5 $\mathrm{m} / \mathrm{s}^{2}…

02:40

Due to continental drift, the North American and European continents are dri…

06:37

Two soccer players start from rest, 48 $\mathrm{m}$ apart. They run directly…

03:41

The three-toed sloth is the slowest-moving land mammal. On the ground, the s…

05:52

A mountain-climbing expedition establishes two intermediate camps, labeled A…

02:41

SSM Two trees have perfectly straight trunks and are both growing perpendicu…

03:45

One afternoon, a couple walks three-fourths of the way around a circular lak…

04:00

A Boeing 747 Jumbo Jet has a length of 59.7 $\mathrm{m}$ . The runway on whi…